Two-terminal integrated circuits with time-varying voltage-current characteristics including phased-locked power supplies

ABSTRACT

A two-terminal IC chip and method thereof. For example, a two-terminal IC chip includes a first chip terminal and a second chip terminal. A first terminal voltage is a voltage of the first chip terminal, a second terminal voltage is a voltage of the second chip terminal, and a chip voltage is equal to a difference between the first terminal voltage and the second terminal voltage. The chip is configured to allow a chip current to flow into the chip at the first chip terminal and out of the chip at the second chip terminal, or to flow into the chip at the second chip terminal and out of the chip at the first chip terminal. The chip current is larger than or equal to zero in magnitude. The chip is further configured to change a relationship between the chip voltage and the chip current with respect to time. The chip is an integrated circuit, and the chip does not include any additional chip terminal other than the first chip terminal and the second chip terminal.

1. CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.201610345806.3, filed May 23, 2016, incorporated by reference herein forall purposes.

2. BACKGROUND OF THE INVENTION

Certain embodiments of the present invention are directed to integratedcircuits. More particularly, some embodiments of the invention providetwo-terminal integrated circuits with time-varying voltage-currentcharacteristics including phase-locked power supplies. Merely by way ofexample, some embodiments of the invention have been applied to driversfor light emitting diodes (LEDs). But it would be recognized that theinvention has a much broader range of applicability.

A single conventional integrated circuit often includes one or moreelectronic circuits on one or more semiconductor materials (e.g.,silicon). The single conventional integrated circuit usually is referredto as an IC, a chip, and/or an IC chip. Additionally, the singleconventional integrated circuit often can be made much smaller than adiscrete circuit that includes one or more discrete components (e.g.,discrete resistor, discrete diode, and/or discrete transistor).

Usually, a conventional IC chip includes three or more terminals thatcan provide interconnections between the internal circuit(s) of the chipand the external environment. Often, the conventional IC chip uses oneterminal to receive a power supply, uses another terminal to provide theground for a current loop, and uses yet another terminal to providecontrol for input and/or output.

For example, a conventional LED driver includes a conventional IC chipthat operates in the switching-power-supply mode. The conventional ICchip includes three or more terminals (e.g., pins) and uses theseterminals to support normal operations. These terminals include a pin toreceive the input rectified AC power, another pin to receive the ICpower supply, and yet another pin to provide input/output control,and/or to provide the chip ground. The input rectified AC power (e.g.,the rectified AC voltage) often periodically becomes zero in magnitudewith respect to the chip ground. In another example, the pin for theinput rectified AC power is connected to a terminal of an externalcapacitor, and the other terminal of the external capacitor is connectedto the pin for the chip ground. The external capacitor often is neededto provide the power supply to the conventional IC chip when the inputrectified AC power (e.g., the rectified AC voltage) periodically becomeszero in magnitude with respect to the chip ground. In yet anotherexample, the conventional IC chip uses the three or more terminals towork with one or more external components (e.g., an inductive winding)outside the chip and convert the received input rectified AC power to aDC power supply for the LED lamps in order to provide a constant LEDcurrent under certain control scheme. The use of external capacitorand/or one or more additional pins for the IC chip often raises thebill-of-materials (BOM) cost of the LED driver.

Hence, it is highly desirable to improve techniques for the integratedcircuit that, for example, is applicable to an LED drive.

3. BRIEF SUMMARY OF THE INVENTION

Certain embodiments of the present invention are directed to integratedcircuits. More particularly, some embodiments of the invention providetwo-terminal integrated circuits with time-varying voltage-currentcharacteristics including phase-locked power supplies. Merely by way ofexample, some embodiments of the invention have been applied to driversfor light emitting diodes. But it would be recognized that the inventionhas a much broader range of applicability.

According to one embodiment, a two-terminal IC chip includes a firstchip terminal and a second chip terminal. A first terminal voltage is avoltage of the first chip terminal, a second terminal voltage is avoltage of the second chip terminal, and a chip voltage is equal to adifference between the first terminal voltage and the second terminalvoltage. The chip is configured to allow a chip current to flow into thechip at the first chip terminal and out of the chip at the second chipterminal, or to flow into the chip at the second chip terminal and outof the chip at the first chip terminal. The chip current is larger thanor equal to zero in magnitude. The chip is further configured to changea relationship between the chip voltage and the chip current withrespect to time. The chip is an integrated circuit, and the chip doesnot include any additional chip terminal other than the first chipterminal and the second chip terminal.

According to another embodiment, a two-terminal IC chip includes a firstchip terminal, a second chip terminal, and a first switch. The chip isconfigured to allow a chip current to flow into the chip at the firstchip terminal and out of the chip at the second chip terminal, or toflow into the chip at the second chip terminal and out of the chip atthe first chip terminal. The chip current is larger than or equal tozero in magnitude. The first switch is configured to receive a drivesignal and be opened or closed in response to the drive signal. The chipis further configured to, in response to the first switch being opened,change the chip current from being larger than zero to being equal tozero in magnitude, and in response to the first switch being closed,change the chip current from being equal to zero to being larger thanzero in magnitude. The chip is an integrated circuit, and the chip doesnot include any additional chip terminal other than the first chipterminal and the second chip terminal.

According to yet another embodiment, a two-terminal IC chip includes afirst chip terminal, a second chip terminal, a first switch configuredto receive a first signal, and a first power supply coupled to the firstswitch. The first switch is configured to be closed during a first timeduration in response to the first signal, and to be open during a secondtime duration in response to the first signal. The first power supply isconfigured to, in response to the first switch being closed, receive afirst power through the first switch and store the received first powerduring the first time duration, and in response to the first switchbeing open, not store any additional power and not allow the storedpower to leak out through the first switch during the second timeduration. The first power supply is further configured to output asecond power during the first time duration and the second timeduration. A first terminal voltage is a voltage of the first chipterminal, a second terminal voltage is a voltage of the second chipterminal, and a chip voltage is equal to a difference between the firstterminal voltage and the second terminal voltage. The chip is configuredto allow a chip current to flow into the chip at the first chip terminaland out of the chip at the second chip terminal, or to flow into thechip at the second chip terminal and out of the chip at the first chipterminal. The chip current is larger than or equal to zero in magnitude.The chip is further configured to, based at least in part on the secondpower, generate at least one selected from a group consisting of thechip voltage and the chip current. The chip is an integrated circuit,and the chip does not include any additional chip terminal other thanthe first chip terminal and the second chip terminal.

According to yet another embodiment, a two-terminal IC chip includes afirst chip terminal and a second chip terminal. The first chip terminalis coupled to a first winding terminal of an inductive winding and afirst diode terminal of a diode. The inductive winding further includesa second winding terminal, and the diode further includes a second diodeterminal. A series of one or more light emitting diodes is coupled tothe second winding terminal and the second diode terminal. The secondwinding terminal and the second diode terminal are configured to receivea rectified AC voltage. The chip is configured to receive an inputvoltage at the first chip terminal and generate a chip current based atleast in part on the input voltage, and the chip current is larger thanor equal to zero in magnitude. Additionally, the chip is furtherconfigured to allow the chip current to flow into the chip at the firstchip terminal and out of the chip at the second chip terminal, or toflow into the chip at the second chip terminal and out of the chip atthe first chip terminal, and change the chip current with respect totime to keep the light-emitting-diode current constant with respect totime even if the input voltage changes within a voltage range and atemperature for the chip changes within a temperature range. The chip isan integrated circuit, and the chip does not include any additional chipterminal other than the first chip terminal and the second chipterminal.

According to yet another embodiment, a two-terminal IC chip for anelectronic system includes a first chip terminal and a second chipterminal. The first chip terminal is coupled to one or more componentsof the electronic system. The electronic system is configured to receivea first signal and generate a second signal based on at leastinformation associated with the first signal. The chip is configured toreceive an input voltage at the first chip terminal and generate a chipcurrent based at least in part on the input voltage. The chip current islarger than or equal to zero in magnitude. Additionally, the chip isfurther configured to allow the chip current to flow into the chip atthe first chip terminal and out of the chip at the second chip terminal,or to flow into the chip at the second chip terminal and out of the chipat the first chip terminal, and change the chip current with respect totime to keep the electronic system operating normally even if the firstsignal changes. The chip is an integrated circuit, and the chip does notinclude any additional chip terminal other than the first chip terminaland the second chip terminal.

Depending upon embodiment, one or more of these benefits may beachieved. These benefits and various additional objects, features andadvantages of the present invention can be fully appreciated withreference to the detailed description and accompanying drawings thatfollow.

4. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram showing an IC chip according to anembodiment of the present invention.

FIG. 2 is a simplified diagram showing an LED driver that includes theIC chip as shown in FIG. 1 according to an embodiment of the presentinvention.

FIG. 3 is a simplified diagram showing an IC chip according to anotherembodiment of the present invention.

5. DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the present invention are directed to integratedcircuits. More particularly, some embodiments of the invention providetwo-terminal integrated circuits with time-varying voltage-currentcharacteristics including phase-locked power supplies. Merely by way ofexample, some embodiments of the invention have been applied to driversfor light emitting diodes. But it would be recognized that the inventionhas a much broader range of applicability.

According to some embodiments, for an IC chip, its terminal to providecontrol for input and/or output is combined with the terminal to receivea power supply or is combined with the terminal to provide the groundfor a current loop. For example, the IC chip includes at most twoterminals, such as a power-supply terminal and a ground terminal. Inanother example, these two terminals of the IC chip not only provide acurrent loop and/or a current flow but also automatically control anentire electronic system. In yet another example, the IC chip works as aone-input-terminal-and-one-output-terminal system.

FIG. 1 is a simplified diagram showing an IC chip according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. One of ordinaryskill in the art would recognize many variations, alternatives, andmodifications. The IC chip 100 includes terminals 110 and 112, aninternal power supply 120, a phase control block 130, controlled switchblocks 140, 142, and 144, power supplies 150, 152, and 154, and functionblocks 160, 162, 164, and 170. For example, each of the terminals 110and 112 is a pin. In another example, the phase control block 130 is aphase controller. In yet another example, each of the controlled switchblocks 140, 142, and 144 is a switch (e.g., a controlled switch). In yetanother example, each of the function blocks 160, 162, 164, and 170 is acomponent configured to perform one or more functions.

In one embodiment, the terminal 110 receives a current and/or voltage114 from outside the IC chip 100, and provides the received currentand/or voltage 114 to one or more components within the IC chip 100, andthe terminal 112 receives a current and/or voltage 124 and/or a currentand/or voltage 116 from one or more components within the IC chip 100,and provides the received current and/or voltage 124 and/or the receivedcurrent and/or voltage 116 to outside the IC chip 100. In anotherembodiment, the terminal 110 receives the current and/or voltage 114from one or more components within the IC chip 100, and provides thereceived current and/or voltage 114 to outside the IC chip 100, and theterminal 112 receives the current and/or voltage 124 and/or the currentand/or voltage 116 from outside the IC chip 100, and provides thereceived current and/or voltage 124 and/or the received current and/orvoltage 116 to one or more components within the IC chip 100. In yetanother embodiment, at one time, the terminal 110 receives the currentand/or voltage 114 from outside the IC chip 100, and provides thereceived current and/or voltage 114 to one or more components within theIC chip 100, and the terminal 112 receives the current and/or voltage124 and/or the current and/or voltage 116 from one or more componentswithin the IC chip 100, and provide the received current and/or voltage124 and/or the received current and/or voltage 116 to outside the ICchip 100; and at another time, the terminal 110 receives the currentand/or voltage 114 from one or more components within the IC chip 100,and provides the received current and/or voltage 114 to outside the ICchip 100, and the terminal 112 receives the current and/or voltage 124and/or the current and/or voltage 116 from outside the IC chip 100, andprovides the received current and/or voltage 124 and/or the receivedcurrent and/or voltage 116 to one or more components within the IC chip100.

As shown in FIG. 1, the terminal 110 receives the current and/or voltage114 from outside the IC chip 100, provides the received current and/orvoltage 114 to the internal power supply 120 during a time duration, andprovides the received current and/or voltage 114 to the function blocks160, 162, 164, and 170 during another time duration, according tocertain embodiments.

In one embodiment, the internal power supply 120 receives the currentand/or voltage 114, and in response outputs a power-supply voltageand/or current 122 to the phase control block 130, the controlled switchblocks 140, 142, and 144, and the function block 170. For example, thephase control block 130 receives the power-supply voltage and/or current122 and in response generates phase-control signals 132, 134, and 136.In another example, the phase control block 130 also generates thecurrent and/or voltage 124. In another embodiment, the controlled switchblock 140 receives the power-supply voltage and/or current 122 and thephase-control signal 132, the controlled switch block 142 receives thepower-supply voltage and/or current 122 and the phase-control signal134, and the controlled switch block 144 receives the power-supplyvoltage and/or current 122 and the phase-control signal 136.

According to one embodiment, the controlled switch block 140, inresponse to the phase-control signal 132, is closed (e.g., turned on)during a time duration and is open (e.g., turned off) during anothertime duration. For example, during the time duration when the controlledswitch block 140 is closed, the controlled switch block 140 uses thepower-supply voltage and/or current 122 to generate a voltage and/orcurrent 141, and outputs the voltage and/or current 141 to the powersupply 150. In another example, the power supply 150 receives power byreceiving the voltage and/or current 141 and stores the received powerwhile providing power (e.g., a voltage and/or current 151) to thefunction block 160. In yet another example, during the another timeduration when the controlled switch block 140 is open, the power supply150 does not receive any power from the controlled switch block 140, andthe energy stored by the power supply 150 is trapped within the powersupply 150 except that the power supply 150 still provides power (e.g.,the voltage and/or current 151) to the function block 160. In yetanother example, during the another time duration when the controlledswitch block 140 is open, the power supply 150 does not receive anypower from the controlled switch block 140, and the energy stored by thepower supply 150 is blocked from leaking out through the controlledswitch block 140 even though the power supply 150 still provides power(e.g., the voltage and/or current 151) to the function block 160.

According to another embodiment, the power supply 150 is phase locked(e.g., by the phase-control signal 132 through the controlled switchblock 140) and self sustaining (e.g., by blocking energy already storedfrom leaking through the controlled switch block 140). For example, whenthe controlled switch block 140 is closed during a time duration asdetermined by the phase-control signal 132, the power supply 150receives and stores additional energy while providing power to thefunction block 160. In another example, when the controlled switch block140 is open during another time duration as determined by thephase-control signal 132, the power supply 150 does not store additionalenergy and the energy stored by the power supply 150 is blocked fromleaking out through the controlled switch block 140, but the powersupply 150 still provides power (e.g., the voltage and/or current 151)to the function block 160.

In one embodiment, the controlled switch block 142, in response to thephase-control signal 134, is closed (e.g., turned on) during a timeduration and is open (e.g., turned off) during another time duration.For example, during the time duration when the controlled switch block142 is closed, the controlled switch block 142 uses the power-supplyvoltage and/or current 122 to generate a voltage and/or current 143, andoutputs the voltage and/or current 143 to the power supply 152. Inanother example, the power supply 152 receives power by receiving thevoltage and/or current 143 and stores the received power while providingpower (e.g., a voltage and/or current 153) to the function block 162. Inyet another example, during the another time duration when thecontrolled switch block 142 is open, the power supply 152 does notreceive any power from the controlled switch block 142, and the energystored by the power supply 152 is trapped within the power supply 152except that the power supply 152 still provides power (e.g., the voltageand/or current 153) to the function block 162. In yet another example,during the another time duration when the controlled switch block 142 isopen, the power supply 152 does not receive any power from thecontrolled switch block 142, and the energy stored by the power supply152 is blocked from leaking out through the controlled switch block 142even though the power supply 152 still provides power (e.g., the voltageand/or current 153) to the function block 162.

In another embodiment, the power supply 152 is phase locked (e.g., bythe phase-control signal 134 through the controlled switch block 142)and self sustaining (e.g., by blocking energy already stored fromleaking through the controlled switch block 142). For example, when thecontrolled switch block 142 is closed during a time duration asdetermined by the phase-control signal 134, the power supply 152receives and stores additional energy while providing power to thefunction block 162. In another example, when the controlled switch block142 is open during another time duration as determined by thephase-control signal 134, the power supply 152 does not store additionalenergy and the energy stored by the power supply 152 is blocked fromleaking out through the controlled switch block 142, but the powersupply 152 still provides power (e.g., the voltage and/or current 153)to the function block 162.

According to one embodiment, the controlled switch block 144, inresponse to the phase-control signal 136, is closed (e.g., turned on)during a time duration and is open (e.g., turned oft) during anothertime duration. For example, during the time duration when the controlledswitch block 144 is closed, the controlled switch block 144 uses thepower-supply voltage and/or current 122 to generate a voltage and/orcurrent 145, and outputs the voltage and/or current 145 to the powersupply 154. In another example, the power supply 154 receives power byreceiving the voltage and/or current 145 and stores the received powerwhile providing power (e.g., a voltage and/or current 155) to thefunction block 164. In yet another example, during the another timeduration when the controlled switch block 144 is open, the power supply154 does not receive any power from the controlled switch block 144, andthe energy stored by the power supply 154 is trapped within the powersupply 154 except that the power supply 154 still provides power (e.g.,the voltage and/or current 155) to the function block 164. In yetanother example, during the another time duration when the controlledswitch block 144 is open, the power supply 154 does not receive anypower from the controlled switch block 144, and the energy stored by thepower supply 154 is blocked from leaking out through the controlledswitch block 144 even though the power supply 154 still provides power(e.g., the voltage and/or current 155) to the function block 164.

According to another embodiment, the power supply 154 is phase locked(e.g., by the phase-control signal 136 through the controlled switchblock 144) and self sustaining (e.g., by blocking energy already storedfrom leaking through the controlled switch block 144). For example, whenthe controlled switch block 144 is closed during a time duration asdetermined by the phase-control signal 136, the power supply 154receives and stores additional energy while providing power to thefunction block 164. In another example, when the controlled switch block144 is open during another time duration as determined by thephase-control signal 136, the power supply 154 does not store additionalenergy and the energy stored by the power supply 154 is blocked fromleaking out through the controlled switch block 144, but the powersupply 154 still provides power (e.g., the voltage and/or current 155)to the function block 164.

In one embodiment, the function block 160 receives the power (e.g., thevoltage and/or current 151) from the power supply 150 and a signal(e.g., the current and/or voltage 114) from the terminal 110, performs afunction on the signal (e.g., the current and/or voltage 114), andgenerates a current and/or voltage 161 based at least in part on thesignal (e.g., the current and/or voltage 114) according to the function.For example, the current and/or voltage 161 is a part of the currentand/or voltage 116.

In another embodiment, the function block 162 receives the power (e.g.,the voltage and/or current 153) from the power supply 152 and a signal(e.g., the current and/or voltage 114) from the terminal 110, performs afunction on the signal (e.g., the current and/or voltage 114), andgenerates a current and/or voltage 163 based at least in part on thesignal (e.g., the current and/or voltage 114) according to the function.For example, the current and/or voltage 163 is a part of the currentand/or voltage 116. In another example, the current and/or voltage 163is different from the current and/or voltage 161.

In yet another embodiment, the function block 164 receives the power(e.g., the voltage and/or current 155) from the power supply 154 and asignal (e.g., the current and/or voltage 114) from the terminal 110,performs a function on the signal (e.g., the current and/or voltage114), and generates a current and/or voltage 165 based at least in parton the signal (e.g., the current and/or voltage 114) according to thefunction. For example, the current and/or voltage 165 is a part of thecurrent and/or voltage 116. In another example, the current and/orvoltage 165 is different from the current and/or voltage 161 and fromthe current and/or voltage 163, and the current and/or voltage 163 isdifferent from the current and/or voltage 161.

In yet another embodiment, the function block 170 receives the power(e.g., the power-supply voltage and/or current 122) from the internalpower supply 120 and a signal (e.g., the current and/or voltage 114)from the terminal 110, performs a function on the signal (e.g., thecurrent and/or voltage 114), and generates a current and/or voltage 175based at least in part on the signal (e.g., the current and/or voltage114) according to the function. For example, the function performed bythe function block 160, the function performed by the function block162, the function performed by the function block 164, and the functionperformed by the function block 170 are different. In yet anotherexample, the current and/or voltage 116 is a combination of the currentand/or voltage 161, the current and/or voltage 163, the current and/orvoltage 165, and the current and/or voltage 175.

As shown in FIG. 1, the power supply 150 also generates a current and/orvoltage 181, the power supply 152 also generates a current and/orvoltage 183, and the power supply 154 also generates a current and/orvoltage 185, according to certain embodiments. For example, the currentand/or voltage 181, the current and/or voltage 183, and the currentand/or voltage 185 are parts of the current and/or voltage 116. In yetanother example, the current and/or voltage 116 is a combination of thecurrent and/or voltage 161, the current and/or voltage 163, the currentand/or voltage 165, the current and/or voltage 175, the current and/orvoltage 181, the current and/or voltage 183, and the current and/orvoltage 185.

In one embodiment, the switch blocks 140, 142, and 144 are controlled tobe turned on or off according to their respective timing arrangements.For example, when the switch block 140, the switch block 142, and/or theswitch block 144 are turned off, the energy stored by the power supply150, the power supply 152, and/or the power supply 154 respectively areblocked from leaking out through the controlled switch block 140, thecontrolled switch block 142, and/or the controlled switch block 144respectively, even though the power supply 150, the power supply 152,and/or the power supply 154 still provides power to the function block160, the function block 162, and/or the function block 164 respectively.In another example, the energy trapped within the power supply 150, thepower supply 152, and/or the power supply 154 respectively is used toprovide power to different function blocks to maintain proper control,even if the power supply (e.g., the current and/or voltage 114 and/orthe current and/or voltage 122) becomes very weak or even lost during atime period.

As discussed above and further emphasized here, FIG. 1 is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. In one embodiment, the IC chip 100 includes two ormore function blocks 170. For example, each of the two or more functionblocks 170 receives the power (e.g., the power-supply voltage and/orcurrent 122) from the internal power supply 120 and a signal (e.g., thecurrent and/or voltage 114) from the terminal 110, performs a functionon the signal (e.g., the current and/or voltage 114), and generates acurrent and/or voltage based at least in part on the signal (e.g., thecurrent and/or voltage 114) according to the function. In anotherexample, the two or more functions performed by the two or more functionblocks 170 respectively are different. In another embodiment, the ICchip 100 includes one or more additional components that are notexplicitly shown in FIG. 1.

FIG. 2 is a simplified diagram showing an LED driver that includes theIC chip 100 as shown in FIG. 1 according to an embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications. For example,the LED driver 200 includes the IC chip 100, an inductive winding 210, adiode 220, diodes 230, 232, 234 and 236, and a capacitor 240. In anotherexample, the LED driver 200 is configured to drive one or more lightemitting diodes (LEDs) 290. In yet another example, the LED driver 200operates in the switching-power-supply mode.

In one embodiment, a terminal 231 of the diode 230 and a terminal 237 ofthe diode 236 receive an AC voltage 250, and in response, the diodes230, 232, 234 and 236 and the capacitor 240 generate a rectified voltage252 (e.g., to provide rectified AC power). In another embodiment, theinductive winding 210 includes terminals 212 and 214, and the diode 220includes terminals 222 and 224. For example, the rectified voltage 252is received by the terminal 222 of the diode 220, and the terminal 224of the diode 220 is connected to the terminal 212 of the inductivewinding 210 and the terminal 110 of the IC chip 100. In another example,the one or more light emitting diodes (LEDs) 290 form a series, whichincludes terminals 292 and 294. In yet another example, the terminal 292is connected to the terminal 222, and the terminal 294 is connected tothe terminal 214.

In yet another embodiment, the terminal 110 of the IC chip 100 receivesa voltage 256 from the terminal 224 and the terminal 212, and inresponse, the IC chip 100 generates a current 254. For example, thevoltage 256 is received by the terminal 110 as the voltage 114, and thecurrent 254 is outputted by the terminal 112 as the current 116. Inanother example, the terminal 112 of the IC chip 100 is biased to apredetermined voltage (e.g., the ground voltage).

In yet another embodiment, the IC chip 100 is biased between the voltageof the terminal 110 (e.g., the voltage 256) and the voltage of theterminal 112, and in response generates a current (e.g., the current254) that flows into the IC chip 100 through the terminal 110 and flowsout of the IC chip 100 through the terminal 112. For example, the ICchip 100 is a two-terminal device that has a current-voltagecharacteristic between the voltage V_(chip) across the IC chip 100(e.g., the voltage of the terminal 110 minus the voltage of the terminal112) and the current I_(chip) flowing through the IC chip 100 (e.g., thecurrent 254). In another example, the current-voltage characteristic ofthe IC chip 100 is represented by an effective resistance R_(chip) ofthe IC chip 100 as shown below:

$\begin{matrix}{R_{chip} = \frac{V_{chip}}{I_{chip}}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

wherein R_(chip) represents the effective resistance of the IC chip 100.Additionally, V_(chip) represents the voltage across the IC chip 100(e.g., the voltage of the terminal 110 minus the voltage of the terminal112), and I_(chip) represents the current flowing through the IC chip100 (e.g., the current 254).

In yet another embodiment, the current-voltage characteristic of the ICchip 100 changes with time. For example, the current-voltagecharacteristic of the IC chip 100 changes periodically with time. Inanother example, within each period, the current-voltage characteristicchanges with time. In yet another embodiment, the effective resistanceR_(chip) of the IC chip 100 changes with time. For example, theeffective resistance R_(chip) of the IC chip 100 changes periodicallywith time. In another example, within each period, the effectiveresistance R_(chip) of the IC chip 100 changes with time.

According to one embodiment, the voltage 256 is received by the IC chip100, and in response, the IC chip 100 generates the current 254. Forexample, the current 254 changes with time. In another example, thecurrent 254 changes periodically with time, and within each period, thecurrent 254 changes with time. In yet another example, the current 254changes with time so that a current 296 that flows through the series ofone or more light emitting diodes 290 remains constant with respect totime.

According to another embodiment, the IC chip 100 of the LED driver 200does not need to rely on an external capacitor to provide the powersupply to the IC chip 100. According to another embodiment, the IC chip100 of the LED driver 200 provides a two-functional-pin solution for theLED driver 200 that reduces the bill-of-materials (BOM) cost but stillmaintains effective constant-current control for the one or more lightemitting diodes (LEDs) 290. For example, the IC chip 100 does notinclude any terminal (e.g., pin) other than the terminals (e.g., pins)110 and 112. In another example, the IC chip 100 can reduce the sizeand/or cost of the overall system (e.g., the LED driver 200), and the ICchip 100 can be used in various consumer electronics.

According to yet another embodiment, the IC chip 100 is configured tokeep the current 296 constant with respect to time even if the voltage256 changes within a voltage range and the temperature of the IC chip100 changes within a temperature range. For example, the IC chip 100 isfurther configured to periodically change the current 254 with respectto time and within each period, change the current 254 with respect totime, to keep the current 296 constant with respect to time even if thevoltage 256 changes within the voltage range and the temperature of theIC chip 100 changes within the temperature range. In another example,the temperature range includes an upper temperature limit equal to 150°C. and a lower temperature limit equal to −40° C. In yet anotherexample, the voltage range includes an upper voltage limit equal to 370V and a lower voltage limit equal to 126 V.

According to yet another embodiment, the IC chip 100 is a controller forthe LED driver 200. For example, the LED driver 200 is configured toreceive the AC voltage 250 and generate the current 296 based on atleast information associated with the AC voltage 250. In anotherexample, the IC chip 100 is configured to generate the current 254,and/or change the current 254 with respect to time, to keep the LEDdriver 200 operating normally even if the AC voltage 250 changes. In yetanother example, the IC chip 100 is further configured to periodicallychange the current 254 with respect to time and within each period,change the current 254 with respect to time, to keep the LED driver 200operating normally even if the AC voltage 250 changes. In yet anotherexample, the LED driver 200 is kept operating normally even if the ACvoltage 250 changes, by keeping the current 296 constant in magnitudewith respect to time even if the AC voltage 250 changes in magnitude.

FIG. 3 is a simplified diagram showing an IC chip according to anotherembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. One of ordinaryskill in the art would recognize many variations, alternatives, andmodifications. The IC chip 300 includes terminals 310 and 312, a lowdropout regular 320, a phase controller 330 (e.g., a phase logiccontroller), a controlled switch and power supply 340, a controlledswitch and power supply 342, an on-time controller 360, a logic-controland gate-drive component 362 (e.g., a driver), a reference-voltagegenerator 370, a demagnetization detector 372, a switch 380 (e.g., atransistor), and a resistor 382.

In one embodiment, the IC chip 300 is the IC chip 100. For example, theterminal 310 is the terminal 110, and the terminal 312 is the terminal112. In another example, the low dropout regular 320 is the internalpower supply 120, and the phase controller 330 is the phase controlblock 130. In yet another example, the controlled switch and powersupply 340 is a combination of the controlled switch block 140 and thepower supply 150, and the controlled switch and power supply 342 is acombination of the controlled switch block 142 and the power supply 152.In yet another example, the on-time controller 360 is the function block160, and the logic-control and gate-drive component 362 is the functionblock 162. In yet another example, the reference-voltage generator 370is the function block 170, and the demagnetization detector 372 isanother function block 170. In another embodiment, the IC chip 300 isthe IC chip 100 that is used in the LED driver 200 as shown in FIG. 2.

In one embodiment, the terminal 310 receives a voltage 314 (e.g., thecurrent and/or voltage 114, or the rectified voltage 252) from outsidethe IC chip 300, and the terminal 312 outputs a current 316 (e.g., thecurrent and/or voltage 116, or the current 254) to outside the IC chip300. For example, the current 316 is larger than or equal to zero inmagnitude. In another example, the voltage 314 is received by the lowdropout regular 320 and the switch 380. In another example, the switch380 is a transistor (e.g., MOSFET). In another embodiment, the lowdropout regular 320 receives the voltage 314, and in response outputs apower-supply voltage 322 to the phase controller 330, the controlledswitch and power supply 340, the controlled switch and power supply 342,the reference-voltage generator 370, and the demagnetization detector372.

According to one embodiment, the reference-voltage generator 370 outputsa reference voltage and/or current 371 to the on-time controller 360.According to another embodiment, the demagnetization detector 372outputs a demagnetization signal 373 to the logic-control and gate-drivecomponent 362. For example, the demagnetization signal 373 indicates thebeginning and the end of each demagnetization period. In anotherexample, the demagnetization period is related to a demagnetizationprocess of the inductive winding 210.

According to yet another embodiment, the phase controller 330 receivesthe power-supply voltage 322, and outputs a phase-control signal 331 tothe controlled switch and power supply 340 and the controlled switch andpower supply 342. For example, the controlled switch and power supply340 includes a switch, and the controlled switch and power supply 342also includes a switch. In another example, the phase-control signal 331indicates the beginning and the end of each turn-on time period and thebeginning and the end of each turn-off time period. In yet anotherexample, the phase-control signal 331 is at a logic level (e.g., a logichigh level) during each turn-on period (e.g., from the beginning to theend of each turn-on time period), and is at another logic level (e.g., alogic low level) during each turn-off time period (e.g., from thebeginning to the end of each turn-off time period).

In one embodiment, during the turn-on time period as indicated by thephase-control signal 331, the switch of the controlled switch and powersupply 340 is closed (e.g., turned on), and during the turn-off timeperiod as indicated by the phase-control signal 331, the switch of thecontrolled switch and power supply 340 is open (e.g., turned off). Forexample, if the switch of the controlled switch and power supply 340 isclosed, the controlled switch and power supply 340 receives powerprovided by the power-supply voltage 322 and stores the received powerwhile providing power (e.g., a power-supply voltage 341) to the on-timecontroller 360. In another example, if the switch of the controlledswitch and power supply 340 is open, the controlled switch and powersupply 340 does not store any additional power provided by thepower-supply voltage 322, and the energy that has already been stored bythe controlled switch and power supply 340 is trapped within thecontrolled switch and power supply 340 except that the controlled switchand power supply 340 still provides power (e.g., the power-supplyvoltage 341) to the on-time controller 360. In yet another example, ifthe switch of the controlled switch and power supply 340 is open, thecontrolled switch and power supply 340 does not store any additionalpower provided by the power-supply voltage 322, and the energy that hasalready been stored by the controlled switch and power supply 340 isblocked from leaking out through the switch of the controlled switch andpower supply 340 even though the controlled switch and power supply 340still provides power (e.g., the power-supply voltage 341) to the on-timecontroller 360.

In another embodiment, during the turn-on time period as indicated bythe phase-control signal 331, the switch of the controlled switch andpower supply 342 is closed (e.g., turned on), and during the turn-offtime period as indicated by the phase-control signal 331, the switch ofthe controlled switch and power supply 342 is open (e.g., turned off).For example, if the switch of the controlled switch and power supply 342is closed, the controlled switch and power supply 342 receives powerprovided by the power-supply voltage 322 and stores the received powerwhile providing power (e.g., a power-supply voltage 343) to thelogic-control and gate-drive component 362. In another example, if theswitch of the controlled switch and power supply 342 is open, thecontrolled switch and power supply 342 does not store any additionalpower provided by the power-supply voltage 322, and the energy that hasalready been stored by the controlled switch and power supply 342 istrapped within the controlled switch and power supply 342 except thatthe controlled switch and power supply 342 still provides power (e.g.,the power-supply voltage 343) to the logic-control and gate-drivecomponent 362. In yet another example, if the switch of the controlledswitch and power supply 342 is open, the controlled switch and powersupply 342 does not store any additional power provided by thepower-supply voltage 322, and the energy that has already been stored bythe controlled switch and power supply 342 is blocked from leaking outthrough the switch of the controlled switch and power supply 342 eventhough the controlled switch and power supply 342 still provides power(e.g., the power-supply voltage 343) to the logic-control and gate-drivecomponent 362.

According to one embodiment, the on-time controller 360 receives thereference voltage and/or current 371 and a current-sensing voltage 383,and in response generates a control signal 361. For example, the on-timecontroller 360 compares the current-sensing voltage 383 with apredetermined voltage limit that corresponds to a predetermined currentlimit. In another example, the control signal 361 indicates whether thecurrent 316 has reached or exceeded the predetermined current limit. Inanother example, the control signal 361 is received by the logic-controland gate-drive component 362, which also receives the demagnetizationsignal 373 and the power-supply voltage 343. In another example, thelogic-control and gate-drive component 362 generates a drive signal 363,which is received by the switch 380 and the demagnetization detector372.

According to another embodiment, the demagnetization detector 372receives the drive signal 363 and the power-supply voltage 322 andgenerates the demagnetization signal 373 based on at least in part onthe drive signal 363. For example, the drive signal 363 is coupled tothe voltage 314 through the parasitic capacitor between the gateterminal 392 of the transistor 380 and the drain terminal 390 of thetransistor 380 (e.g., C_(gd)). In another example, the demagnetizationsignal 373 indicates the beginning and the end of each demagnetizationperiod. In another example, the demagnetization period is related to thedemagnetization process of the inductive winding 210.

In one embodiment, the switch 380 receives the drive signal 363, and isclosed or opened by the drive signal 363. For example, the drive signal363 is a pulse-width-modulation (PWM) signal, which changes between alogic low level and a logic high level. In another example, thepulse-width-modulation (PWM) signal remains at the logic high levelduring a pulse width. In another embodiment, if the drive signal 363 isat the logic high level, the switch 380 is turned on and thus closed,and if the drive signal 363 is at the logic low level, the switch 380 isturned off and thus opened.

In yet another embodiment, the switch 380 (e.g., a transistor) includesterminals 390, 392, and 394, and the resistor 382 includes terminals 396and 398. For example, the terminal 390 of the transistor 380 isconnected to the terminal 310 of the IC chip 300, and the terminal 392of the transistor 380 is configured to receive the drive signal 363. Inanother example, the terminal 394 of the transistor 380 is connected tothe terminal 396 of the resistor 382, and the terminal 398 of theresistor 382 is connected to the terminal 310 of the IC chip 300.

As shown in FIG. 3, the transistor 380 and the resistor 382 are biasedbetween the voltage of the terminal 310 and the voltage of the terminal312 according to certain embodiments. For example, if the transistor 380is turned on, the current 316 flows into the IC chip 300 at the terminal310, through the transistor 380 and the resistor 382, and out of the ICchip 300 at the terminal 312. In another example, the current-sensingvoltage 383 represents the magnitude of the current 316.

According to one embodiment, the on-time controller 360 receives thepower-supply voltage 341, the reference voltage and/or current 371, andthe current-sensing voltage 383, and generates the control signal 361,and the demagnetization detector 372 receives the drive signal 363 andthe power-supply voltage 322 and generates the demagnetization signal373. For example, the control signal 361 indicates whether the current316 has reached or exceeded the predetermined current limit, and thedemagnetization signal 373 indicates the beginning and the end of eachdemagnetization period (e.g., related to the demagnetization process ofthe inductive winding 210). In another example, both the control signal361 and the demagnetization signal 373 are received by the logic-controland gate-drive component 362.

According to another embodiment, the logic-control and gate-drivecomponent 362 uses the control signal 361 and the demagnetization signal373 to determine the pulse width of the drive signal 363. For example,if the demagnetization signal 373 indicates the end of a demagnetizationperiod (e.g., related to the demagnetization process of the inductivewinding 210), the pulse width of the drive signal 363 starts and theswitch 392 changes from being turned off to being turned on so that thecurrent 316 starts to increase from zero in magnitude. In anotherexample, if the control signal 361 indicates the current 316 has reachedor exceeded the predetermined current limit, the pulse width of thedrive signal 363 ends and the switch 392 changes from being turned on tobeing turned off so that the current 316 drops to zero in magnitude.

As discussed above and further emphasized here, FIG. 3 is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. For example, the IC chip 300 also includes a bandgapcircuit (e.g., a temperature-independent voltage-reference circuit). Inanother example, the IC chip 300 also includes a reference-currentgenerator, in replacement of or in addition to the reference-voltagegenerator 370.

According to certain embodiments, the IC chip 100 (e.g., the IC chip300) is an integrated circuit. For example, the IC chip 100 (e.g., theIC chip 300) includes two or more semiconductor devices that areintegrated, and has a control architecture with multiple functionalblocks. In another example, the IC chip 100 (e.g., the IC chip 300)includes no more than two terminals (e.g., the terminals 110 and 112).In yet another example, the IC chip 100 can be used in variouselectronic systems (e.g., the LED driver 200).

According to some embodiments, the IC chip 100 (e.g., the IC chip 300)is an integrated circuit that includes no more than two terminals (e.g.,pins). For example, the integrated circuit of the IC chip 100 includestwo or more active semiconductor devices (e.g., one or more diodesand/or one or more transistors) that are integrated. In another example,the IC chip 100 (e.g., the IC chip 300) generates an internal signal(e.g., the drive signal 363), which is a pulse-width-modulation (PWM)signal. In yet another example, the IC chip 100 (e.g., the IC chip 300)has a current-voltage characteristic between the voltage across the ICchip 100 and the current flowing through the IC chip 100. In yet anotherexample, the current-voltage characteristic of the IC chip 100 isperiodic with respect to time, and within each period, thecurrent-voltage characteristic (e.g., the current-voltage analogbehavior) changes with time.

According to certain embodiments, the IC chip 100 (e.g., the IC chip300) includes one or more mixed-signal IC architectures, circuits and/orcomponents. For example, the phase controller 330 and the logic-controland gate-drive component 362 each are a digital circuit. In anotherexample, the low dropout regular 320, the controlled switch and powersupply 340, the controlled switch and power supply 342, and thereference-voltage generator 370 each are an analog circuit. In yetanother example, the on-time controller 360 and the demagnetizationdetector 372 each include an analog circuit and a digital circuit.

According to some embodiments, the IC chip 100 (e.g., the IC chip 300)is an integrated circuit that includes no more than two terminals (e.g.,pins) and that also includes one or more controlled switch blocks (e.g.,the controlled switch blocks 140, 142, and/or 144) and one or more powersupplies (e.g., the power supplies 150, 152, and/or 154). For example,the IC chip 100 (e.g., the IC chip 300) generates an internal signal(e.g., the drive signal 363), which is a pulse-width-modulation (PWM)signal. In another example, the one or more controlled switch blocks(e.g., the controlled switch blocks 140, 142, and/or 144) receive one ormore corresponding phase-control signals (e.g., the phase-controlsignals 132, 134, and/or 136) respectively, and are opened or closed bythe one or more corresponding phase-control signals (e.g., thephase-control signals 132, 134, and/or 136) respectively. In yet anotherexample, the one or more controlled switch blocks (e.g., the controlledswitch blocks 140, 142, and/or 144) are opened or closed according totheir respectively timing arrangements (e.g., as determined by the oneor more corresponding phase-control signals respectively).

In one embodiment, if a controlled switch block (e.g., the controlledswitch block 140, 142, or 144) is closed (e.g., turned on) during a timeduration, a corresponding power supply that is connected to thecontrolled switch block (e.g., the power supply 150, 152, or 154)receives power through the controlled switch block and stores thereceived power while providing power to a corresponding function blockthat is connected to the power supply (e.g., the function block 160,162, or 164). In another embodiment, if the controlled switch block(e.g., the controlled switch block 140, 142, or 144) is open (e.g.,turned off) during another time duration, the corresponding power supplythat is connected to the controlled switch block (e.g., the power supply150, 152, or 154) does not receive any power from the controlled switchblock, and the energy stored by the corresponding power supply istrapped within this power supply, except that this power supply stillprovides power to the corresponding function block that is connected tothis power supply (e.g., the function block 160, 162, or 164). In yetanother embodiment, if the controlled switch block (e.g., the controlledswitch block 140, 142, or 144) is open (e.g., turned off) during anothertime duration, the corresponding power supply that is connected to thecontrolled switch block (e.g., the power supply 150, 152, or 154) doesnot receive any power from the controlled switch block, and the energystored by the corresponding power supply is blocked from leaking outthrough the controlled switch block even though this power supply stillprovides power to the corresponding function block that is connected tothis power supply (e.g., the function block 160, 162, or 164).

According to certain embodiments, the IC chip 100 (e.g., the IC chip300) is an integrated circuit that includes no more than two terminals(e.g., pins). In one embodiment, the two-terminal IC chip 100 (e.g., thetwo-terminal IC chip 300) is a controller for an electronic system(e.g., an electronic system that includes the LED driver 200 and the oneor more LEDs 290). In another embodiment, the two-terminal controller100 (e.g., the two-terminal controller 300) enables an electronic systemto perform normal and/or stable operations even if the externalconditions of the electronic system changes. For example, an electronicsystem includes the LED driver 200 and the one or more LEDs 290, and thetwo-terminal controller 100 (e.g., the two-terminal controller 300)keeps the current 296 that flows through the one or more light emittingdiodes 290 constant with respect to time, even if the AC voltage 250changes in amplitude (e.g., the peak magnitude of the AC voltage 250changes from one voltage value to another voltage value).

According to some embodiments, the IC chip 100 (e.g., the IC chip 300)is a two-terminal controller that can use a same terminal (e.g., theterminal 110 and/or the terminal 310) as an input terminal during a timeduration and as an output terminal during another time duration. Forexample, the two-terminal controller 100 (e.g., the two-terminalcontroller 300) implements a signal processing mechanism (e.g., a signalprocessing algorithm), and the signal processing mechanism is used todetermine the relationship between the time duration and the anothertime duration. In another example, during a pulse width of thepulse-width-modulation (PWM) signal 363, the two-terminal controller 300uses the terminal 310 as an output terminal to allow the current 316that is larger than zero in magnitude to flow into the controller 300 atthe terminal 310 and flow out of the controller 300 at the terminal 312.In yet another example, during a pulse width of thepulse-width-modulation (PWM) signal 363, the two-terminal controller 100(e.g., the two-terminal controller 300) outputs the current 316 that islarger than zero in magnitude as the drive current to the one or morelight emitting diodes (LEDs) 290. In yet another example, during ademagnetization period (e.g., related to the demagnetization process ofthe inductive winding 210) that is outside the pulse width of thepulse-width-modulation (PWM) signal 363, the two-terminal controller 300uses the terminal 310 as an input terminal to receive the voltage 314and process (e.g., detect and/or sample) the received voltage 314 todetermine the end of the demagnetization period, which corresponds tothe beginning of the next pulse width. In yet another example, thevoltage 314 is coupled to the drive signal 363 through the parasiticcapacitor between the gate terminal 392 of the transistor 380 and thedrain terminal 390 of the transistor 380 (e.g., C_(gd)).

According to some embodiments, the IC chip 100 (e.g., the IC chip 300)is a two-terminal controller that can adaptively change its output(e.g., the current and/or voltage 116, the current 254, and/or thecurrent 316) in response to the change of its input (e.g., the currentand/or voltage 114, the rectified voltage 252, and/or the voltage 314),so that an electronic system (e.g., an electronic system including theLED driver 200, the one or more LEDs 290, and the two-terminalcontroller 100) can perform normal and/or stable operations (e.g., keepthe current 296 that flows through the one or more light emitting diodes290 constant with respect to time). For example, in response to thechange in amplitude of its input (e.g., the change in peak magnitude ofthe current and/or voltage 114, the rectified voltage 252, and/or thevoltage 314), the IC chip 100 (e.g., the IC chip 300) changes its output(e.g., the current and/or voltage 116, the current 254, and/or thecurrent 316) through a control mechanism (e.g., by changing the pulsewidth and/or the duty cycle of the drive signal 363) so that the current296 that flows through the one or more light emitting diodes 290 remainsconstant with respect to time.

In another example, if the AC voltage 250 changes in amplitude (e.g.,the peak magnitude of the AC voltage 250 changes from one voltage valueto another voltage value), the amplitude of the current and/or voltage114, the rectified voltage 252, and/or the voltage 314 (e.g., the peakmagnitude of the current and/or voltage 114, the rectified voltage 252,and/or the voltage 314) also changes. In yet another example, if theamplitude of the current and/or voltage 114, the rectified voltage 252,and/or the voltage 314 becomes smaller, the pulse width and/or the dutycycle of the drive signal 363 becomes larger so that the current 296that flows through the one or more light emitting diodes 290 remainsconstant with respect to time.

In yet another example, the two-terminal controller 100 (e.g., thetwo-terminal controller 300) adaptively changes its output (e.g., thecurrent and/or voltage 116, the current 254, and/or the current 316) inresponse to the change of its input (e.g., the current and/or voltage114, the rectified voltage 252, and/or the voltage 314) by changing arelationship (e.g., the current-voltage characteristic of the IC chip100 as shown in Equation 1) between the controller input and thecontroller output, so that the current 296 that flows through the one ormore light emitting diodes 290 remains constant with respect to time. Inanother example, without such change in the relationship, therelationship between the controller input and the controller outputvaries with time periodically; in contrast, with such change in therelationship, the relationship between the controller input and thecontroller output varies with time but not periodically.

According to another embodiment, a two-terminal IC chip (e.g., the ICchip 100 and/or the IC chip 300) includes a first chip terminal (e.g.,the terminal 110 and/or the terminal 310) and a second chip terminal(e.g., the terminal 112 and/or the terminal 312). A first terminalvoltage (e.g., the voltage 256) is a voltage of the first chip terminal,a second terminal voltage is a voltage of the second chip terminal, anda chip voltage (e.g., the voltage V_(chip) across the IC chip 100) isequal to a difference between the first terminal voltage and the secondterminal voltage. The chip is configured to allow a chip current (e.g.,the current 254) to flow into the chip at the first chip terminal andout of the chip at the second chip terminal, or to flow into the chip atthe second chip terminal and out of the chip at the first chip terminal.The chip current is larger than or equal to zero in magnitude. The chipis further configured to change a relationship (e.g., thecurrent-voltage characteristic of the IC chip 100 as shown inEquation 1) between the chip voltage and the chip current with respectto time. The chip (e.g., the IC chip 100 and/or the IC chip 300) is anintegrated circuit, and the chip does not include any additional chipterminal other than the first chip terminal (e.g., the terminal 110and/or the terminal 310) and the second chip terminal (e.g., theterminal 112 and/or the terminal 312). For example, the two-terminal ICchip is implemented according to at least FIG. 1, FIG. 2, and/or FIG. 3.

In another example, the two-terminal IC chip is further configured toperiodically change the relationship (e.g., the current-voltagecharacteristic of the IC chip 100 as shown in Equation 1) between thechip voltage and the chip current with respect to time, and within eachperiod, change the relationship between the chip voltage and the chipcurrent with respect to time. In yet another example, the two-terminalIC chip also includes a switch (e.g., the switch 380) and a resistor(e.g., the resistor 382) coupled to the switch. The switch is configuredto receive a drive signal (e.g., the drive signal 363), and be opened orclosed in response to the drive signal. The chip is further configuredto, in response to the switch being opened, change the chip current(e.g., the current 254) from being larger than zero to being equal tozero in magnitude, and in response to the switch being closed, changethe chip current (e.g., the current 254) from being equal to zero tobeing larger than zero in magnitude.

In yet another example, the chip is further configured to, in responseto the switch being closed, allow the chip current to flow through theswitch and the resistor. The chip current being larger than zero inmagnitude. In yet another example, the drive signal (e.g., the drivesignal 363) is a pulse-width-modulation signal corresponding to a pulsewidth for each modulation period. In yet another example, thetwo-terminal IC chip also includes a driver (e.g., the driver 362)configured to receive a first signal (e.g., the demagnetization signal373) and a second signal (e.g., the control signal 361) and generate thedrive signal (e.g., the drive signal 363). The driver is furtherconfigured to, in response to the first signal (e.g., thedemagnetization signal 373) indicating an end of a demagnetizationperiod, change the drive signal to start the pulse width, and inresponse to the second signal (e.g., the control signal 361) indicatingthe chip current (e.g., the current 254) has reached or exceeded apredetermined current limit, change the drive signal to end the pulsewidth. In yet another example, the driver is further configured to, inresponse to the first signal indicating the end of the demagnetizationperiod, change the drive signal to close the switch and increase thechip current (e.g., the current 254) from zero in magnitude, and inresponse to the second signal indicating the chip current has reached orexceeded the predetermined current limit, change the drive signal toopen the switch and decrease the chip current to zero in magnitude.

In yet another example, the first chip terminal (e.g., the terminal 110and/or the terminal 310) is coupled to a first winding terminal (e.g.,the terminal 212) of an inductive winding (e.g., the inductive winding210) and a first diode terminal (e.g., the terminal 224) of a diode(e.g., the diode 220). The inductive winding further includes a secondwinding terminal (e.g., the terminal 214), and the diode furtherincludes a second diode terminal (e.g., the terminal 222). A series ofone or more light emitting diodes (e.g., the one or more LEDs 290) iscoupled to the second winding terminal and the second diode terminal.The second winding terminal and the second diode terminal are configuredto receive a rectified AC voltage (e.g., the rectified voltage 252). Inyet another example, the two-terminal IC chip is further configured toreceive the first terminal voltage (e.g., the voltage 256) at the firstchip terminal (e.g., the terminal 110 and/or the terminal 310) andgenerate the chip current (e.g., the current 254) based at least in parton the first terminal voltage. In yet another example, the chip current(e.g., the current 254) is configured to flow between the first chipterminal and the second chip terminal to affect a light-emitting-diodecurrent (e.g., the current 296) flowing through the series of the one ormore light emitting diodes (e.g., the one or more LEDs 290). In yetanother example, the two-terminal IC chip is further configured tochange the chip current (e.g., the current 254) with respect to time tokeep the light-emitting-diode current (e.g., the current 296) constantwith respect to time. In yet another example, the two-terminal IC chip(e.g., the IC chip 100 and/or the IC chip 300) is further configured toperiodically change the chip current (e.g., the current 254) withrespect to time and within each period, change the chip current (e.g.,the current 254) with respect to time, to keep the light-emitting-diodecurrent (e.g., the current 296) constant with respect to time.

In yet another example, the two-terminal IC chip (e.g., the IC chip 100and/or the IC chip 300) also includes a controlled switch (e.g., thecontrolled switch 140, the controlled switch 142, and/or the controlledswitch 144) configured to receive a control signal (e.g., thephase-control signal 132, the phase-control signal 134, thephase-control signal 136, and/or the phase-control signal 331), and apower supply (e.g., the power supply 150, the power supply 152, and/orthe power supply 154) coupled to the controlled switch. The controlledswitch is further configured to be closed during a first time durationin response to the control signal, and to be open during a second timeduration in response to the control signal. The power supply isconfigured to, in response to the controlled switch being closed,receive a first power (e.g., the voltage and/or current 141, the voltageand/or current 143, and/or the voltage and/or current 145) through thecontrolled switch and store the received first power during the firsttime duration, and in response to the controlled switch being open, notstore any additional power and not allow stored power to leak outthrough the controlled switch during the second time duration. The powersupply (e.g., the power supply 150, the power supply 152, and/or thepower supply 154) is further configured to output a second power (e.g.,the voltage and/or current 151, the voltage and/or current 153, thevoltage and/or current 155, the power-supply voltage 341, and/or thepower-supply voltage 343) during the first time duration and the secondtime duration. In yet another example, the chip voltage (e.g., thevoltage V_(chip) across the IC chip 100) is equal to the first terminalvoltage minus the second terminal voltage.

According to yet another embodiment, a two-terminal IC chip (e.g., theIC chip 100 and/or the IC chip 300) includes a first chip terminal(e.g., the terminal 110 and/or the terminal 310), a second chip terminal(e.g., the terminal 112 and/or the terminal 312), and a first switch(e.g., the switch 380). The chip is configured to allow a chip current(e.g., the current 254) to flow into the chip at the first chip terminaland out of the chip at the second chip terminal, or to flow into thechip at the second chip terminal and out of the chip at the first chipterminal. The chip current is larger than or equal to zero in magnitude.The first switch is configured to receive a drive signal (e.g., thedrive signal 363) and be opened or closed in response to the drivesignal. The chip is further configured to, in response to the firstswitch being opened, change the chip current from being larger than zeroto being equal to zero in magnitude, and in response to the first switchbeing closed, change the chip current from being equal to zero to beinglarger than zero in magnitude. The chip is an integrated circuit, andthe chip does not include any additional chip terminal other than thefirst chip terminal (e.g., the terminal 110 and/or the terminal 310) andthe second chip terminal (e.g., the terminal 112 and/or the terminal312). For example, the two-terminal IC chip is implemented according toat least FIG. 1, FIG. 2, and/or FIG. 3.

In another example, the drive signal (e.g., the drive signal 363) is apulse-width-modulation signal corresponding to a pulse width for eachmodulation period. In yet another example, the two-terminal IC chip alsoincludes a driver (e.g., the driver 362) configured to receive a firstsignal (e.g., the demagnetization signal 373) and a second signal (e.g.,the control signal 361) and generate the drive signal (e.g., the drivesignal 363). The driver is further configured to, in response to thefirst signal (e.g., the demagnetization signal 373) indicating an end ofa demagnetization period, change the drive signal to start the pulsewidth, and in response to the second signal (e.g., the control signal361) indicating the chip current (e.g., the current 254) has reached orexceeded a predetermined current limit, change the drive signal to endthe pulse width. In yet another example, the driver is furtherconfigured to, in response to the first signal indicating the end of thedemagnetization period, change the drive signal to close the firstswitch and increase the chip current (e.g., the current 254) from zeroin magnitude, and in response to the second signal indicating the chipcurrent has reached or exceeded the predetermined current limit, changethe drive signal to open the first switch and decrease the chip currentto zero in magnitude.

In yet another example, the first chip terminal (e.g., the terminal 110and/or the terminal 310) is coupled to a first winding terminal (e.g.,the terminal 212) of an inductive winding (e.g., the inductive winding210) and a first diode terminal (e.g., the terminal 224) of a diode(e.g., the diode 220). The inductive winding further includes a secondwinding terminal (e.g., the terminal 214), and the diode furtherincludes a second diode terminal (e.g., the terminal 222). A series ofone or more light emitting diodes (e.g., the one or more LEDs 290) iscoupled to the second winding terminal and the second diode terminal.The second winding terminal and the second diode terminal are configuredto receive a rectified AC voltage (e.g., the rectified voltage 252).

In yet another example, the two-terminal IC chip is further configuredto receive an input voltage (e.g., the voltage 256) at the first chipterminal (e.g., the terminal 110 and/or the terminal 310) and generatethe chip current (e.g., the current 254) based at least in part on thereceived input voltage. In yet another example, the chip current (e.g.,the current 254) is configured to flow between the first chip terminaland the second chip terminal to affect a light-emitting-diode current(e.g., the current 296) flowing through the series of the one or morelight emitting diodes (e.g., the one or more LEDs 290). In yet anotherexample, the two-terminal IC chip is further configured to change thechip current (e.g., the current 254) with respect to time to keep thelight-emitting-diode current (e.g., the current 296) constant withrespect to time. In yet another example, the two-terminal IC chip (e.g.,the IC chip 100 and/or the IC chip 300) is further configured toperiodically change the chip current (e.g., the current 254) withrespect to time and within each period, change the chip current (e.g.,the current 254) with respect to time, to keep the light-emitting-diodecurrent (e.g., the current 296) constant with respect to time.

In yet another example, the two-terminal IC chip (e.g., the IC chip 100and/or the IC chip 300) also includes a second switch (e.g., the switch140, the switch 142, and/or the switch 144) configured to receive acontrol signal (e.g., the phase-control signal 132, the phase-controlsignal 134, the phase-control signal 136, and/or the phase-controlsignal 331), and a power supply (e.g., the power supply 150, the powersupply 152, and/or the power supply 154) coupled to the second switch.The second switch is further configured to be closed during a first timeduration in response to the control signal, and to be open during asecond time duration in response to the control signal. The power supplyis configured to, in response to the second switch being closed, receivea first power (e.g., the voltage and/or current 141, the voltage and/orcurrent 143, and/or the voltage and/or current 145) through the secondswitch and store the received first power during the first timeduration, and in response to the second switch being open, not store anyadditional power and not allow stored power to leak out through thesecond switch during the second time duration. The power supply (e.g.,the power supply 150, the power supply 152, and/or the power supply 154)is further configured to output a second power (e.g., the voltage and/orcurrent 151, the voltage and/or current 153, the voltage and/or current155, the power-supply voltage 341, and/or the power-supply voltage 343)during the first time duration and the second time duration.

According to yet another embodiment, a two-terminal IC chip (e.g., theIC chip 100 and/or the IC chip 300) includes a first chip terminal(e.g., the terminal 110 and/or the terminal 310), a second chip terminal(e.g., the terminal 112 and/or the terminal 312), a first switch (e.g.,the switch 140, the switch 142, and/or the switch 144) configured toreceive a first signal (e.g., the phase-control signal 132, thephase-control signal 134, the phase-control signal 136, and/or thephase-control signal 331), and a first power supply (e.g., the powersupply 150, the power supply 152, and/or the power supply 154) coupledto the first switch. The first switch is configured to be closed duringa first time duration in response to the first signal, and to be openduring a second time duration in response to the first signal. The firstpower supply (e.g., the power supply 150, the power supply 152, and/orthe power supply 154) is configured to, in response to the first switch(e.g., the switch 140, the switch 142, and/or the switch 144) beingclosed, receive a first power (e.g., the voltage and/or current 141, thevoltage and/or current 143, and/or the voltage and/or current 145)through the first switch and store the received first power during thefirst time duration, and in response to the first switch being open, notstore any additional power and not allow the stored power to leak outthrough the first switch during the second time duration. The firstpower supply (e.g., the power supply 150, the power supply 152, and/orthe power supply 154) is further configured to output a second power(e.g., the voltage and/or current 151, the voltage and/or current 153,the voltage and/or current 155, the power-supply voltage 341, and/or thepower-supply voltage 343) during the first time duration and the secondtime duration. A first terminal voltage (e.g., the voltage 256) is avoltage of the first chip terminal (e.g., the terminal 110 and/or theterminal 310), a second terminal voltage is a voltage of the second chipterminal (e.g., the terminal 112 and/or the terminal 312), and a chipvoltage (e.g., the voltage V_(chip) across the IC chip 100) is equal toa difference between the first terminal voltage and the second terminalvoltage. The chip is configured to allow a chip current (e.g., thecurrent 254) to flow into the chip at the first chip terminal and out ofthe chip at the second chip terminal, or to flow into the chip at thesecond chip terminal and out of the chip at the first chip terminal. Thechip current is larger than or equal to zero in magnitude. The chip(e.g., the IC chip 100 and/or the IC chip 300) is further configured to,based at least in part on the second power (e.g., the voltage and/orcurrent 151, the voltage and/or current 153, the voltage and/or current155, the power-supply voltage 341, and/or the power-supply voltage 343),generate at least one selected from a group consisting of the chipvoltage (e.g., the voltage V_(chip) across the IC chip 100) and the chipcurrent (e.g., the current 254). The chip (e.g., the IC chip 100 and/orthe IC chip 300) is an integrated circuit, and the chip does not includeany additional chip terminal other than the first chip terminal (e.g.,the terminal 110 and/or the terminal 310) and the second chip terminal(e.g., the terminal 112 and/or the terminal 312). For example, thetwo-terminal IC chip is implemented according to at least FIG. 1, FIG.2, and/or FIG. 3.

In another example, the two-terminal IC chip also includes a driver(e.g., the driver 362) configured to receive the second power (e.g., thepower-supply voltage 343) and generate a drive signal (e.g., the drivesignal 363), and a second switch (e.g., the switch 380) configured toreceive the drive signal and be opened or closed in response to thedrive signal. The chip is further configured to, in response to theswitch being opened, change the chip current (e.g., the current 254)from being larger than zero to being equal to zero in magnitude, and inresponse to the switch being closed, change the chip current (e.g., thecurrent 254) from being equal to zero to being larger than zero inmagnitude.

In yet another example, the drive signal (e.g., the drive signal 363) isa pulse-width-modulation signal corresponding to a pulse width for eachmodulation period. In yet another example, the two-terminal IC chipfurther includes a controller (e.g., the phase controller 130 and/or thephase controller 330) configured to generate the first signal (e.g., thephase-control signal 132, the phase-control signal 134, thephase-control signal 136, and/or the phase-control signal 331). Thefirst signal (e.g., the phase-control signal 132, the phase-controlsignal 134, the phase-control signal 136, and/or the phase-controlsignal 331) is at a first logic level during the first time duration,and the first signal is at a second logic level during the second timeduration. The second logic level is different from the first logiclevel.

In yet another example, the two-terminal IC chip (e.g., the IC chip 100and/or the IC chip 300) also includes a second power supply (e.g., theinternal power supply 120 and/or the low dropout regular 320). Thesecond power supply is configured to receive a third power (e.g., thecurrent and/or voltage 114, the voltage 256, and/or the voltage 314)from the first chip terminal (e.g., the terminal 110 and/or the terminal310), generate a fourth power (e.g., the power-supply voltage and/orcurrent 122 and/or the power-supply voltage 322) based at least in parton the third power, and output the fourth power to the controller (e.g.,the phase controller 130 and/or the phase controller 330) and the firstswitch (e.g., the switch 140, the switch 142, and/or the switch 144). Inyet another example, the first switch (e.g., the switch 140, the switch142, and/or the switch 144) is further configured to, in response to thefirst switch being closed, output the first power (e.g., the voltageand/or current 141, the voltage and/or current 143, and/or the voltageand/or current 145) based at least in part on the fourth power (e.g.,the power-supply voltage and/or current 122 and/or the power-supplyvoltage 322).

In yet another example, the first chip terminal (e.g., the terminal 110and/or the terminal 310) is coupled to a first winding terminal (e.g.,the terminal 212) of an inductive winding (e.g., the inductive winding210) and a first diode terminal (e.g., the terminal 224) of a diode(e.g., the diode 220). The inductive winding further includes a secondwinding terminal (e.g., the terminal 214), and the diode furtherincludes a second diode terminal (e.g., the terminal 222). A series ofone or more light emitting diodes (e.g., the one or more LEDs 290) iscoupled to the second winding terminal and the second diode terminal.The second winding terminal and the second diode terminal are configuredto receive a rectified AC voltage (e.g., the rectified voltage 252). Inyet another example, the chip voltage (e.g., the voltage V_(chip) acrossthe IC chip 100) is equal to the first terminal voltage minus the secondterminal voltage.

According to yet another embodiment, a two-terminal IC chip (e.g., theIC chip 100 and/or the IC chip 300) includes a first chip terminal(e.g., the terminal 110 and/or the terminal 310) and a second chipterminal (e.g., the terminal 112 and/or the terminal 312). The firstchip terminal is coupled to a first winding terminal (e.g., the terminal212) of an inductive winding (e.g., the inductive winding 210) and afirst diode terminal (e.g., the terminal 224) of a diode (e.g., thediode 220). The inductive winding further includes a second windingterminal (e.g., the terminal 214), and the diode further includes asecond diode terminal (e.g., the terminal 222). A series of one or morelight emitting diodes (e.g., the one or more LEDs 290) is coupled to thesecond winding terminal and the second diode terminal. The secondwinding terminal and the second diode terminal are configured to receivea rectified AC voltage (e.g., the rectified voltage 252). The chip(e.g., the IC chip 100 and/or the IC chip 300) is configured to receivean input voltage (e.g., the voltage 256) at the first chip terminal andgenerate a chip current (e.g., the current 254) based at least in parton the input voltage, and the chip current is larger than or equal tozero in magnitude. Additionally, the chip is further configured to allowthe chip current to flow into the chip at the first chip terminal andout of the chip at the second chip terminal, or to flow into the chip atthe second chip terminal and out of the chip at the first chip terminal,and change the chip current with respect to time to keep thelight-emitting-diode current (e.g., the current 296) constant withrespect to time even if the input voltage (e.g., the voltage 256)changes within a voltage range and a temperature for the chip (e.g., thetemperature of the IC chip 100 and/or the IC chip 300) changes within atemperature range. The chip (e.g., the IC chip 100 and/or the IC chip300) is an integrated circuit, and the chip does not include anyadditional chip terminal other than the first chip terminal and thesecond chip terminal. For example, the two-terminal IC chip isimplemented according to at least FIG. 1, FIG. 2, and/or FIG. 3.

In another example, the two-terminal IC chip is further configured toperiodically change the chip current with respect to time and withineach period, change the chip current with respect to time, to keep thelight-emitting-diode current constant with respect to time even if theinput voltage changes within the voltage range and the temperature forthe chip changes within the temperature range. In yet another example,the temperature range includes an upper temperature limit equal to 150°C. and a lower temperature limit equal to −40° C. In yet anotherexample, the voltage range includes an upper voltage limit equal to 370V and a lower voltage limit equal to 126 V.

According to yet another embodiment, a two-terminal IC chip (e.g., theIC chip 100 and/or the IC chip 300) for an electronic system (e.g., theLED driver 200) includes a first chip terminal (e.g., the terminal 110and/or the terminal 310) and a second chip terminal (e.g., the terminal112 and/or the terminal 312). The first chip terminal is coupled to oneor more components (e.g., the inductive winding 210 and/or the diode220) of the electronic system (e.g., the LED driver 200). The electronicsystem (e.g., the LED driver 200) is configured to receive a firstsignal (e.g., the AC voltage 250) and generate a second signal (e.g.,the current 296) based on at least information associated with the firstsignal. The chip (e.g., the IC chip 100 and/or the IC chip 300) isconfigured to receive an input voltage (e.g., the voltage 256) at thefirst chip terminal (e.g., the terminal 110) and generate a chip current(e.g., the current 254) based at least in part on the input voltage. Thechip current is larger than or equal to zero in magnitude. Additionally,the chip is further configured to allow the chip current to flow intothe chip at the first chip terminal and out of the chip at the secondchip terminal, or to flow into the chip at the second chip terminal andout of the chip at the first chip terminal, and change the chip currentwith respect to time to keep the electronic system (e.g., the LED driver200) operating normally even if the first signal (e.g., the AC voltage250) changes. The chip is an integrated circuit, and the chip does notinclude any additional chip terminal other than the first chip terminaland the second chip terminal. For example, the two-terminal IC chip isimplemented according to at least FIG. 1, FIG. 2, and/or FIG. 3.

In another example, the two-terminal IC chip (e.g., the IC chip 100and/or the IC chip 300) is further configured to periodically change thechip current with respect to time and within each period, change thechip current with respect to time, to keep the electronic system (e.g.,the LED driver 200) operating normally even if the first signal changes.In another example, the first signal is a voltage signal (e.g., the ACvoltage 250), and the second signal is a current signal (e.g., thecurrent 296). In yet another example, the two-terminal IC chip isfurther configured to change the chip current with respect to time tokeep the current signal (e.g., the current 296) constant in magnitudewith respect to time even if the voltage signal (e.g., the AC voltage250) changes in magnitude. In yet another example, the two-terminal ICchip is further configured to periodically change the chip current withrespect to time and within each period, change the chip current withrespect to time, to keep the current signal (e.g., the current 296)constant in magnitude with respect to time even if the voltage signal(e.g., the AC voltage 250) changes in magnitude. In yet another example,the two-terminal IC chip (e.g., the IC chip 100 and/or the IC chip 300)is a controller for the electronic system (e.g., the LED driver 200).

For example, some or all components of various embodiments of thepresent invention each are, individually and/or in combination with atleast another component, implemented using one or more softwarecomponents, one or more hardware components, and/or one or morecombinations of software and hardware components. In another example,some or all components of various embodiments of the present inventioneach are, individually and/or in combination with at least anothercomponent, implemented in one or more circuits, such as one or moreanalog circuits and/or one or more digital circuits. In yet anotherexample, various embodiments and/or examples of the present inventioncan be combined.

Although specific embodiments of the present invention have beendescribed, it will be understood by those of skill in the art that thereare other embodiments that are equivalent to the described embodiments.Accordingly, it is to be understood that the invention is not to belimited by the specific illustrated embodiments, but only by the scopeof the appended claims.

1. A two-terminal IC chip, the chip comprising: a first chip terminal;and a second chip terminal; wherein: a first terminal voltage is avoltage of the first chip terminal; a second terminal voltage is avoltage of the second chip terminal; and a chip voltage is equal to adifference between the first terminal voltage and the second terminalvoltage; wherein the chip is configured to allow a chip current to flowinto the chip at the first chip terminal and out of the chip at thesecond chip terminal, or to flow into the chip at the second chipterminal and out of the chip at the first chip terminal, the chipcurrent being larger than or equal to zero in magnitude; wherein thechip is further configured to change a relationship between the chipvoltage and the chip current with respect to time; wherein: the chip isan integrated circuit; and the chip does not include any additional chipterminal other than the first chip terminal and the second chipterminal.
 2. The two-terminal IC chip of claim 1 is further configuredto: periodically change the relationship between the chip voltage andthe chip current with respect to time; and within each period, changethe relationship between the chip voltage and the chip current withrespect to time.
 3. The two-terminal IC chip of claim 1, and furthercomprising: a switch; and a resistor coupled to the switch; wherein theswitch is configured to: receive a drive signal; and be opened or closedin response to the drive signal; wherein the chip is further configuredto: in response to the switch being opened, change the chip current frombeing larger than zero to being equal to zero in magnitude; and inresponse to the switch being closed, change the chip current from beingequal to zero to being larger than zero in magnitude.
 4. Thetwo-terminal IC chip of claim 3 wherein the chip is further configuredto, in response to the switch being closed, allow the chip current toflow through the switch and the resistor, the chip current being largerthan zero in magnitude.
 5. The two-terminal IC chip of claim 3 whereinthe drive signal is a pulse-width-modulation signal corresponding to apulse width for each modulation period.
 6. The two-terminal IC chip ofclaim 5, and further comprising: a driver configured to receive a firstsignal and a second signal and generate the drive signal; wherein thedriver is further configured to: in response to the first signalindicating an end of a demagnetization period, change the drive signalto start the pulse width; and in response to the second signalindicating the chip current has reached or exceeded a predeterminedcurrent limit, change the drive signal to end the pulse width.
 7. Thetwo-terminal IC chip of claim 6 wherein the driver is further configuredto: in response to the first signal indicating the end of thedemagnetization period, change the drive signal to close the switch andincrease the chip current from zero in magnitude; and in response to thesecond signal indicating the chip current has reached or exceeded thepredetermined current limit, change the drive signal to open the switchand decrease the chip current to zero in magnitude.
 8. The two-terminalIC chip of claim 1 wherein the first chip terminal is coupled to a firstwinding terminal of an inductive winding and a first diode terminal of adiode, the inductive winding further including a second windingterminal, the diode further including a second diode terminal, a seriesof one or more light emitting diodes being coupled to the second windingterminal and the second diode terminal, the second winding terminal andthe second diode terminal being configured to receive a rectified ACvoltage.
 9. The two-terminal IC chip of claim 8 is further configured toreceive the first terminal voltage at the first chip terminal andgenerate the chip current based at least in part on the first terminalvoltage.
 10. The two-terminal IC chip of claim 9 wherein the chipcurrent is configured to flow between the first chip terminal and thesecond chip terminal to affect a light-emitting-diode current flowingthrough the series of the one or more light emitting diodes.
 11. Thetwo-terminal IC chip of claim 10 is further configured to change thechip current with respect to time to keep the light-emitting-diodecurrent constant with respect to time.
 12. The two-terminal IC chip ofclaim 11 is further configured to periodically change the chip currentwith respect to time and within each period, change the chip currentwith respect to time, to keep the light-emitting-diode current constantwith respect to time.
 13. The two-terminal IC chip of claim 1, andfurther comprising: a controlled switch configured to receive a controlsignal; and a power supply coupled to the controlled switch; wherein thecontrolled switch is further configured to be: closed during a firsttime duration in response to the control signal; and open during asecond time duration in response to the control signal; wherein thepower supply is configured to: in response to the controlled switchbeing closed, receive a first power through the controlled switch andstore the received first power during the first time duration; and inresponse to the controlled switch being open, not store any additionalpower and not allow stored power to leak out through the controlledswitch during the second time duration; wherein the power supply isfurther configured to output a second power during the first timeduration and the second time duration.
 14. The two-terminal IC chip ofclaim 1 wherein the chip voltage is equal to the first terminal voltageminus the second terminal voltage.
 15. A two-terminal IC chip, the chipcomprising: a first chip terminal; a second chip terminal; and a firstswitch; wherein the chip is configured to allow a chip current to flowinto the chip at the first chip terminal and out of the chip at thesecond chip terminal, or to flow into the chip at the second chipterminal and out of the chip at the first chip terminal, the chipcurrent being larger than or equal to zero in magnitude; wherein thefirst switch is configured to: receive a drive signal; and be opened orclosed in response to the drive signal; wherein the chip is furtherconfigured to: in response to the first switch being opened, change thechip current from being larger than zero to being equal to zero inmagnitude; and in response to the first switch being closed, change thechip current from being equal to zero to being larger than zero inmagnitude; wherein: the chip is an integrated circuit; and the chip doesnot include any additional chip terminal other than the first chipterminal and the second chip terminal.
 16. The two-terminal IC chip ofclaim 15 wherein the drive signal is a pulse-width-modulation signalcorresponding to a pulse width for each modulation period.
 17. Thetwo-terminal IC chip of claim 16, and further comprising: a driverconfigured to receive a first signal and a second signal and generatethe drive signal; wherein the driver is further configured to: inresponse to the first signal indicating an end of a demagnetizationperiod, change the drive signal to start the pulse width; and inresponse to the second signal indicating the chip current has reached orexceeded a predetermined current limit, change the drive signal to endthe pulse width.
 18. The two-terminal IC chip of claim 17 wherein thedriver is further configured to: in response to the first signalindicating the end of the demagnetization period, change the drivesignal to close the first switch and increase the chip current from zeroin magnitude; and in response to the second signal indicating the chipcurrent has reached or exceeded the predetermined current limit, changethe drive signal to open the first switch and decrease the chip currentto zero in magnitude.
 19. The two-terminal IC chip of claim 15 whereinthe first chip terminal is coupled to a first winding terminal of aninductive winding and a first diode terminal of a diode, the inductivewinding further including a second winding terminal, the diode furtherincluding a second diode terminal, a series of one or more lightemitting diodes being coupled to the second winding terminal and thesecond diode terminal, the second winding terminal and the second diodeterminal being configured to receive a rectified AC voltage.
 20. Thetwo-terminal IC chip of claim 19 is further configured to receive aninput voltage at the first chip terminal and generate the chip currentbased at least in part on the received input voltage.
 21. Thetwo-terminal IC chip of claim 20 wherein the chip current is configuredto flow between the first chip terminal and the second chip terminal toaffect a light-emitting-diode current flowing through the series of theone or more light emitting diodes.
 22. The two-terminal IC chip of claim21 is further configured to change the chip current with respect to timeto keep the light-emitting-diode current constant with respect to time.23. The two-terminal IC chip of claim 22 is further configured toperiodically change the chip current with respect to time and withineach period, change the chip current with respect to time, to keep thelight-emitting-diode current constant with respect to time.
 24. Thetwo-terminal IC chip of claim 15, and further comprising: a secondswitch configured to receive a control signal; and a power supplycoupled to the second switch; wherein the second switch is furtherconfigured to be: closed during a first time duration in response to thecontrol signal; and open during a second time duration in response tothe control signal; wherein the power supply is configured to: inresponse to the second switch being closed, receive a first powerthrough the second switch and store the received first power during thefirst time duration; and in response to the second switch being open,not store any additional power and not allow stored power to leak outthrough the second switch during the second time duration; wherein thepower supply is further configured to output a second power during thefirst time duration and the second time duration. 25.-32. (canceled) 33.A two-terminal IC chip, the chip comprising: a first chip terminal; anda second chip terminal; wherein the first chip terminal is coupled to afirst winding terminal of an inductive winding and a first diodeterminal of a diode, the inductive winding further including a secondwinding terminal, the diode further including a second diode terminal, aseries of one or more light emitting diodes being coupled to the secondwinding terminal and the second diode terminal, the second windingterminal and the second diode terminal being configured to receive arectified AC voltage; wherein the chip is configured to: receive aninput voltage at the first chip terminal and generate a chip currentbased at least in part on the input voltage, the chip current beinglarger than or equal to zero in magnitude; allow the chip current toflow into the chip at the first chip terminal and out of the chip at thesecond chip terminal, or to flow into the chip at the second chipterminal and out of the chip at the first chip terminal; and change thechip current with respect to time to keep the light-emitting-diodecurrent constant with respect to time even if the input voltage changeswithin a voltage range and a temperature for the chip changes within atemperature range; wherein: the chip is an integrated circuit; and thechip does not include any additional chip terminal other than the firstchip terminal and the second chip terminal.
 34. The two-terminal IC chipof claim 33 is further configured to periodically change the chipcurrent with respect to time and within each period, change the chipcurrent with respect to time, to keep the light-emitting-diode currentconstant with respect to time even if the input voltage changes withinthe voltage range and the temperature for the chip changes within thetemperature range.
 35. The two-terminal IC chip of claim 33 wherein thetemperature range includes an upper temperature limit equal to 150° C.and a lower temperature limit equal to −40° C.
 36. The two-terminal ICchip of claim 33 wherein the voltage range includes an upper voltagelimit equal to 370 V and a lower voltage limit equal to 126 V.
 37. Atwo-terminal IC chip for an electronic system, the chip comprising: afirst chip terminal; and a second chip terminal; wherein the first chipterminal is coupled to one or more components of the electronic system,the electronic system being configured to receive a first signal andgenerate a second signal based on at least information associated withthe first signal; wherein the chip is configured to: receive an inputvoltage at the first chip terminal and generate a chip current based atleast in part on the input voltage, the chip current being larger thanor equal to zero in magnitude; allow the chip current to flow into thechip at the first chip terminal and out of the chip at the second chipterminal, or to flow into the chip at the second chip terminal and outof the chip at the first chip terminal; and change the chip current withrespect to time to keep the electronic system operating normally even ifthe first signal changes; wherein: the chip is an integrated circuit;and the chip does not include any additional chip terminal other thanthe first chip terminal and the second chip terminal.
 38. Thetwo-terminal IC chip of claim 37 is further configured to periodicallychange the chip current with respect to time and within each period,change the chip current with respect to time, to keep the electronicsystem operating normally even if the first signal changes.
 39. Thetwo-terminal IC chip of claim 37 wherein: the first signal is a voltagesignal; and the second signal is a current signal.
 40. The two-terminalIC chip of claim 39 is further configured to change the chip currentwith respect to time to keep the current signal constant in magnitudewith respect to time even if the voltage signal changes in magnitude.41. The two-terminal IC chip of claim 40 is further configured toperiodically change the chip current with respect to time and withineach period, change the chip current with respect to time, to keep thecurrent signal constant in magnitude with respect to time even if thevoltage signal changes in magnitude.
 42. The two-terminal IC chip ofclaim 37 is a controller for the electronic system.